Here's the biggest recurring theme in the IRS controversy — the one about alleged targeting of conservative groups seeking tax-exempt status.

Throughout the yearlong investigation, congressional Republicans and Democrats have not only highlighted their own evidence but also taken the same evidence and drawn diametrically opposed conclusions.

The latest example came Wednesday afternoon, at a subcommittee hearing of the House Oversight and Government Reform Committee. Officially, the subject was a separate IRS issue. But lawmakers couldn't help veering off into a row over Lois Lerner's missing emails.

Lerner was head of the IRS exempt organizations division, overseeing the tax-exempt applications. Her computer hard drive crashed in 2011, destroying many months of archived emails. The committee members all seem convinced Lerner is culpable of something. Democrats and a Treasury Department inspector general call it gross mismanagement. Republicans say it's political scheming and destroying evidence.

On Wednesday, committee Republicans asked IRS Commissioner John Koskinen about a new discovery: It turns out the IRS has an internal messaging system, called OCS.

In a chain of emails, shown to Koskinen at the hearing, Lerner asks if OCS messages are searchable, and she gets an answer.

To Rep. Jim Jordan, R-Ohio, the emails show Lerner was trying to cover her tracks. He pointed to the first sentence of the second email, that "OCS messages are not set to automatically save."

Jordan's interpretation: "Miss Lerner says, 'Wow. I know I've gotten rid of the emails, when the computer crashed two years earlier. But I better double-check on this intraoffice, instant messaging capability we have here at the Internal Revenue Service.' And she says 'Perfect' when she learns that it's not traceable, not trackable, not stored."

But Rep. Gerald Connolly, D-Va., said Lerner's "Perfect" comment concerned the third paragraph, where she was advised to treat OCS messages as potentially searchable.

Jordan burst out, "That is the most ridiculous interpretation — there is no one with any common sense that would reach that conclusion my colleague reached. No one."

A long way to a short question.

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